EXO 1745-248 is an 11 Hz Eclipsing Pulsar
ATel #2929; T. E. Strohmayer (NASA/GSFC), C. B. Markwardt (NASA/GSFC)
on 13 Oct 2010; 05:29 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Craig B. Markwardt (email@example.com)
Subjects: X-ray, Request for Observations, Binary, Globular Cluster, Neutron Star, Transient, Pulsar
Referred to by ATel #: 2932, 2933, 2939, 2940, 2946, 2952, 2958, 2974, 3000, 3044, 3264, 3714, 3892
RXTE pointed observations of the ongoing outburst of EXO 1745-284
(ATEL #2919, #2920, #2922, #2924)
began at approximately 2010-10-13 at 00:13 UTC, for an exposure of 3.2
ksec. The flux of the source is approximately 95 mCrab (2-10 keV).
The observation reveals strong pulsations at a barycentric frequency of
In addition, we observe an eclipse ingress/egress during the
observation, beginning at 00:50:24.5 UTC and ending at 00:58:56.2 UTC,
implying an eclipse duration of 511.7 Â± 1 sec.
The eclipse is not associated with earth occultation of the RXTE
satellite, and X-ray pulsations disappear during the eclipse,
firmly establishing the X-ray pulsator and eclipser as the same object.
The intensity level during the eclipse is consistent
with contributions solely from instrumental and X-ray background. Both
the ingress and egress are observed and are quite sharp, with the
transition occurring in less than 1 second.
A thermonuclear X-ray burst
was also observed beginning near 00:37. The burst lasts for 150 seconds,
a duration suggestive of significant hydrogen in the accreted matter.
Further RXTE observations are being planned. Observations at other
wavelengths are strongly encouraged.